The present invention relates to a device capable of being operated by remote control for driving a part on a vehicle.
As the part on a vehicle stated above, a door locking device, an automatic antenna device, a window opening and closing device, etc. can be cited, and as a conventional driving source for these driving devices, there are known an electromagnetic motor and an electromagnetic valve.
However, recently, there is a tendency that an ultrasonic actuator or an ultrasonic linear actuator, which is small and light, produces neither mechanical noise nor electromagnetic noises, and has further a simple structure, as a motor or a valve driving the part on a vehicle described above.
For example, as a prior art door locking device, a device is known, which is so constructed that locking or unlocking operation can be effected by operating manually a door locking knob linked with a door locking portion, and at the same time the locking or unlocking operation can be effected also by remote control by means of an actuator disposed in the door locking portion stated above. As the actuator described above, a solenoid, an electromagnetic motor and a traveling wave type ultrasonic motor (disclosed e.g. in JP-UM-A-63-34868) is used.
However, in the prior art door locking device, in the case where a solenoid is used as the actuator, working noise thereof is remarkable, which impairs silentness in the passenger room of the vehicle and in the case where an electromagnetic motor is used, not only working noise thereof is remarkable but also it requires a mechanism for transforming a rotational movement into a linear movement, which gives rise to increase in weight and produces also noises in a radio set. On the other hand, in the case where a traveling wave type ultrasonic motor is used, although it can be intended to reduce working noise and electromagnetic noises, it has drawbacks that it requires also a mechanism for transforming a rotational movement into a linear movement, which gives rise to increase in weight, and that the energy conversion efficiency is low. Further, e.g. as a prior art automatic antenna device, an antenna is known, which is so constructed that a flexible cable is inserted in a telescopic type antenna rod mounted extensively in the axial direction, one end of this cable being connected with the extremity portion of the antenna rod stated above, while the other end thereof is connected with a driving mechanism, and the antenna rod stated above is extended or contracted by moving the cable stated above in the axial direction of the antenna rod by means of the driving mechanism described above started together with a radio switch, etc. in the passenger room, linked therewith.
In such an automatic antenna device, as the driving mechanism stated above, a mechanism is known, which is so constructed that the rotation of the motor is reduced by means of a worm mechanism and transmitted to a pinion gear, the rotation of which is further transmitted to a rack formed on one side of the cable to be transformed into a linear movement, so that the cable is moved in the axial direction of the antenna member.
However the prior art automatic antenna device described previously had a drawback that since the motor is used as the actuator, the motor produces noises at the extending/contracting operation of the antenna rod and these noises are received by the radio set together with the broadcast, which worsens the reception state.
Further there was another drawback that since it is necessary to dispose a driving mechanism for transforming the rotational movement of the motor into the linear movement, the weight of the device increases and further, since the worm gear, for which the transmission efficiency is low, is used, the energy conversion efficiency is low.
In addition, there was still another drawback that at the stop of the motor, since the extending/contracting movement of the antenna rod is restricted by the self stopping effect of the worm gear in the driving mechanism, even in the case where it is necessary to extend/contract manually the antenna rod because of damage to the motor, etc. the operation thereof is practically impossible.